Support is requested for a Hitachi Model L-8800 amino acid analyzer to perform a wide spectrum of amino acid analyses for a relatively large group of biomedical researchers at the University of Texas Medical Branch at Galveston (UTMB). The Hitachi analyzer employs a post-column methodology utilizing either colorimetric detection (ninhydrin) or fluorescence detection (omicron-phthaladehyde). Furthermore, the L-8800 can perform a wide variety of analytical methodologies including protein/peptide hydrolyzates, physiological fluids, and hydrolyzates of specialized samples, such as those of fibrous proteins, or proteins that have been chemically or posttranslationally modified. Compositional analysis and precise analysis of protein/peptide concentrations will be among the critically important applications of the Hitachi analyzer, as well as analysis of free amino acids in samples of physiological fluids and tissue extracts. The requested Hitachi analyzer will replace a 15-year old retired Beckman 6300 and an aging 13-year old Applied Biosystems 420H Ptc-amino acid analyzer. The Hitachi analyzer will be used by many NIH-funded research investigators at UTMB; a representative user group, with 14 funded NIH grants, is described that includes five major and five minor NIH-funded users, who include multidisciplinary investigators from several departments at UTMB, e.g. Human Biological Chemistry and Genetics, Microbiology and Toxicology, Preventive Medicine and Community Health, and the Marine Biomedical Institute. Examples of biomedical questions or diseases under investigation by these users include gastrointestinal bacterial pathogenesis, xenobiotics, diabetic and senile cataractogenesis, environmental toxicology and mutagenesis. The amino acid analyzer will be operated and maintained in the Protein Chemistry Core within the UTMB Biomolecular Resource Facility, a longstanding research support facility that includes five cores, namely, Protein Chemistry, Peptide Synthesis, Protein Expression and Purification, Mass Spectrometry, and Proteomics. Together, these Cores provide a wide range of research services for the entire University campus, including multiple campus research centers. Acquisition of the requested instrumentation will significantly enhance the ability of NIH-funded investigators to conduct their ongoing hypothesis-driven research and, moreover, will extend their research opportunities in the future to higher levels of productivity and scientific impact.